Previous studies in this laboratory have demonstrated that structural framework of the cell nucleus termed the nuclear matrix is transiently associated with replicating DNA. In this project emphasis will be placed on defining the organizational and functional properties of a matrix-associated replicational complex and the interaction of matrix proteins with replicating nucleosomes. To begin with the in vitro association of replicating DNA with the nuclear matrix will be studied including the analysis of replicational intermediates. This will be followed by an analysis of the structural localization of DNA polymerase alpha. Finally the replicative activity of isolated matrices with attached nucleosomes and DNA polymerase alpha will be investigated. The next series of experiments will deal with the interaction of matrix proteins with matrix attached nucleosomes. This will be studied by fractionation techniques, two dimensional electrophoresis and crosslinking experiments. Particular emphasis will be given to identifying specific associations between matrix proteins and nucleosomal proteins. Progress in these studies will lead to a similar analysis of 125I heavy labeled replicating nucleosomes and their interaction with the supporting matrix structure.